Apparatus for the longitudinal cutting of narrow strips

ABSTRACT

Apparatus for the longitudinal cutting of narrow strips of web material such as paper, foil, and the like, by means of several circular knives wherein a flat annular spring presses each such knife against a portion of a hub on which each knife is seated. One spring and one knife are seated on each hub, and a spring on one hub bears against a knife on an adjacent hub. Each spring is resilient and capable of flexing so as to be positively seated in place on its respective hub.

United States Patent [1 1 Jakob [451 July 15,1975

[ APPARATUS FOR THE LONGITUDINAL CUTTING OF NARROW STRIPS [75] Inventor: Hans Jakob, Darmstadt-Eberstadt,

Germany [73] Assignee: Maschinenfabrik GOEBEL GmbI-I,

Darmstadt, Germany 221 Filed: Jan. 28, 1974 211 App]. No.: 437,395

[30] Foreign Application Priority Data Jan. 27, 1973 Germany 2304092 [52] US. Cl. 83/665; 83/481; 83/698 [51] Int. Cl. B26d 1/14 [58] Field of Search 83/665, 666, 698, 676,

[56] References Cited UNITED STATES PATENTS 1,673,336 6/1928 Lehmicke 83/500 X 3,805,661 4/1974 Tumomaala 83/666 FOREIGN PATENTS OR APPLICATIONS 305,586 6/1919 Germany 83/501 319.326 3/1917 Germany 83/501 310,796 6/1919 Germany 83/501 Primary Examiner-J. M. Meister Attorney, Agent, or Firm-Watson, Cole, Grindle & Watson [5 7 ABSTRACT Apparatus for the longitudinal cutting of narrow strips of web material such as paper, foil, and the like, by means of several circular knives wherein a flat annular spring presses each such knife against a portion of a hub on which each knife is seated. One spring and one knife are seated on each hub, and a spring on one hub bears against a knife on an adjacent hub. Each spring is resilient and capable of flexing so as to be positively seated in place on its respective hub.

1 Claim, 3 Drawing Figures SHEET 13'??? WW JUL APPARATUS FOR THE LONGITUDINAL CUTTING OF NARROW STRIPS This invention relates to an apparatus for the longitudinal cutting of narrow strips of web material such as paper, foil, and the like, by means of several circular knives, wherein each such knife is mounted on a hub or driving collar and is capable of being pressed against a portion thereof by means of a spring. Each knife and its spring are mounted together on an individual hub, and each spring is made to bear against a knife on an adjacent hub.

In apparatuses heretofore provided for the cutting of narrow strips from web material, the web in most instances passes between two shafts, one of which having circular knives mounted thereon, and the other shaft having grooves or counterknives thereon for accommodating such knives. One shaft normally drives the other, or the shafts are rotated as the moving web passes therebetween.

Whenever strips ofa different width are to be cut, as, for example, based on a change of the production program of the machine containing the knives, the knives and their grooves or counterknives must be adjusted correspondingly. This can be achieved for example by inserting or removing washers between the knives or the hubs carrying the knives; these washers often having a thickness of only a few fractions of a millimeter. In order to remove these washers, or in order to be able to insert them, it is necessary to relax the clamping by which the knives or the hubs holding said knives are held on their shaft.

Furthermore, it should be noted that, for the cutting of particularly narrow strips, the knives must be relatively adjustable by small distances which requires that the hubs carrying the knives be made as narrow as possible.

An arrangement for the cutting of narrow strips is disclosed in German Pat. No. 305,586, wherein each circular knife is set on a hub, and wherein a plateshaped and circular spring is attached to the same hub, which spring bears against the circular knife attached to an adjacent hub. Accordingly, whenever the width of the strips to be cut and thus the position assumed by the hubs carrying the circular knives in relation to one another are to be changed, the springs because of their elasticity very often become unseated whenever the hubs are removed from one another, whereupon the springs quite easily become wedged in between adjacent hubs. Should only a single spring not assume the desired position, several of the knives will not reach the desired position during the subsequent clamping of the hubs on the shaft assigned to them, so that a width of a strip is cut which deviates from the predetermined production program. When a plurality of hubs are aligned along a shaft with springs corresponding to the number of hubs, it becomes quite cumbersome to remove the springs from their undesirable position. Moreover, the removal process is very time consuming since a number of springs may have become undesirably wedged between the hubs, or other springs may become unseated during the aligning process of one spring. This becomes more troublesome whenever the circular knives are closely adjacent one another, so that the springs cannot be returned directly by hand into their correct position but only with the 'aido'f a. tool. In

many instances several operating personnel are needed for such purpose.

Another type apparatus is disclosed, for example, in Austrian Pat. No. 76,978 wherein circular knives are pressed by means of endless helical springs against the seat of the hub related to each knife, or against the relative counter knife. This arrangement is however not suitable for the cutting of very narrow strips since the circular knives must be pressed at a predetermined pressure against their respective hubs or against their respective counter knife, for which purpose the endless spring must produce a predetermined force. Accordingly, precise geometric dimensions for the knives, hubs and coil must be maintained.

In accordance with the present invention, an apparatus is provided for longitudinally cutting the narrowest strips possible. A readjustment for one strip width to another is capable of being achieved as simply as possible while at the same time assuring the necessary spring bias of each circular knife against its hub or against its respective counter knife.

Such is effected in that each spring is connected with its respective hub and is movable relative to its hub in both a radial as well as an axial direction by only an insignificant amount.

The present apparatus includes an annular groove provided in each hub for the reception of each flat annular spring, the diameter of each groove being slightly larger than the inner diameter of each spring. Also, a lateral wall of each annular groove is inclined toward the longitudinal axis of the shaft supporting the hub by an angle less than Moreover, each spring is resilient and is capable of flexing in an annular direction, radial legs comprising the spring being so interconnected as to permit such flexing.

In such manner each spring is more positively seated on its respective hub even if the hub spacing is changed by means of washers and the like during the operation of the apparatus. Thus, the springs cannot be wedged in between the hubs, and the time consuming and troublesome alignment of the springs is completely avoided. The readjustment from one width to another of the-strips to be cut is therefore easily and quickly facilitated. In addition, the setting periods for the apparatus are decreased by a considerable amount, so that the effective running time of the machine is accordingly increased. Furthermore, readjustment can be accomplished in a very simple manner by a single operator.

Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the invention when considered .in conjunction with the accompanying drawings wherein:

FIG. 1 is a longitudinal sectional view taken through the apparatus according to the invention;

FIG. 2 is a top view of one of the springs used in the invention and at a reduced scale relative to FIG. 1; and

FIG. 3 is a view similar to FIG. 2 showing the spring legs expanded when mounted in place.

The counter grooves or knives for each of the circusince they provided bearings at opposite ends thereoof in a machine frame. One of these bearings'can be removably mounted to facilitate mounting of the circular knives and their hubs on to the shaft. This may be necessary, for example, to facilitate the sliding of a number of circular knives or hubs carrying such circularknives on to shaft 1 in an axial direction.

An annular flange 2 is mounted on shaft 1 in the vicinity of one of the two bearings thereon. Near the other of such bearings, shaft 1 is provided with a thread 3 and a nut 4 engaged therewith. A plurality of aligned annular hubs 6 are provided along the shaft on a section 5 having a larger diamter than the threaded shaft diameter. Hubs 6, 6a, 6b, 6c and 6d are shown in FIG. 1, although fewer than or more than five of such hubs may be provided without departing from the invention. The hubs are keyed on the shaft for rotation therewith and are mounted on section 5 against flange 2 by means of a bushing 7.

Whenever the spacing between adjacent hubs is to be altered, nut 4 and bushing 7 are removed from shaft 1 so that washers or the like may be inserted between the hubs. Of course, no such spacers are used for the cutting of the narrowest possible strips which depends on the relative thickness of adjacent hubs. Also, bushing 7 is designed to accommodate the number of hubs with or without spacers required for a specific operation.

An annular groove 8 is provided in each of the hubs, one lateral wall 9 of which is inclined at an angle to the longitudinal axis 10 of shaft 1, which angle is less than 90.

An annular spring 11, in the form shown for example in FIG. 2, engages with annular groove 8. Spring 11 is in the form of an annular flat plate having a plurality of adjacent inner sections 12 interconnecting adjacent pairs of radially extending legs 12a and 12b. The inner ends of these legs are interconnected to sections 12 along an inner circle 120 which corresponds approximately to that of the inner diameter of annular groove 8. Adjacent outer sections 13 interconnect adjacent pairs of legs 12a and 12b at their outer ends. An annular ring 14 is formed on each hub, each ring defining the opposite wall of each annular groove 8. Accordingly, spring 11 may be forced over the edge of ring 14 of each hub. During such assembly, sections 12 bend somewhat and then snap into annular groove 8. Legs 12a and 12b are therefore flexed from their radially extending positions in the relaxed state of FIG. 2 to their relatively separated positions of FIG. 3 as when seated within grooves 8. Thus, each spring 11 is seated both in a radial as well as in an axial direction so firmly that it can be shifted at most by only insignificant amounts. In order to release the spring from its hub, the application of force is also needed. Furthermore, it is understandable that, with such construction, spring 11 cannot be unseated in any undesirable manner from its respective hub.

Each hub 6 is also provided with an annular seat 15 on which a respective circular knife 16 is supported. Because of the flexure of spring 11, it will be assured that circular knife 16 is pressed against a shoulder 17 located on each hub. This pressure against knife 16 is also transmitted to its corresponding counter knife with which knife 16 cooperates.

It should be noted that annular seat 15 for circular knife 16 is disposed on one side of each hub 6, while annular groove 8 is located for the accommodation of spring 11 on the other side of each hub. Furthermore, one lateral wall 9 of annular groove 8 is disposed obliquely in relation to the longitudinal axis 10 of knife shaft 1 and thus of the longitudinal axisof each hub, and is thus inclined in relation to the latter by an angle which is less than 90. Annular groove 8 is of such a width that spring 11 is allowed a certain freedom of axial movement. Since the inner diameter of spring 11 is less than the diameter of groove 8, tension develops in each spring 11, as a result of which circular knife 16 associated with a spring 11 of an adjacent hub is pressed against shoulder 17 or against the counter knife associated with circular knife 16. Each spring 11 flexes in the manner shown in FIG. 3 when inserted within grooves 8.

Since each spring 11 is disposed in such a way that it is associated with that circular knife 16 which is located adjacent the spring on each adjoining hub, dimensions will result which permit flexure and tension of each spring, and wherein the thickness 18 of each hub can be maintained as small as possible. In such manner, it is also possible to maintain distances 19, as between adjacent blades 16, as small as possible. Also, since lateral wall 9 of each annular groove 8 slopes at an angle to axis 10, a certain freedom of movement is provided for each spring 11. As a result, it becomes possible to dispose annular groove 8 in each hub in such a way that it will be covered up at least partially or even completely by annular seat 15 for circular knife 16. It is possible, for example, that edge 20 of the shoulder 17 located to the right in FIG. 1, be made to lie on the same radius as the right edge 21 of annular groove 8. But it is also possible that edge 20 be made to lie further to the left or that edge 21 be made to lie further to the right, as a result of which a certain overlapping occurs. Moreover, the material of each hub 6 can be exploited as much as possible, in that thickness 18 of each hub 6 can be made as small as possible, and each hub 6 can be maintained so rigid that circular knife 16 is guided and is precisely seated.

Obviously, hub 6a lying adjacent flange 2 need not be provided with an annular groove 8 since no spring 11 need be seated thereon. Also, hub 6 lying adjacent bushing 7 need not be provided with an annular seat 15 since no knife 16 is supported by this hub. As heretofore mentioned, any number of hubs may be disposed along shaft 1 adjacent one another without departing from the scope of the present invention. Of course, the length of section 5 would need to be accordingly altered.

Many other modifications and variations are made possible within the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practical otherwise than as specifically described.

What is claimed is:

1. Apparatus for the longitudinal slitting of narrow strips of web material such as paper, foil and the like, comprising a rotatable shaft, a plurality of annular adjacent hubs mounted along said shaft for rotation therewith, circular knivesand flat annular flexible springs seated on each of said hubs, radially extending shoulder projections on said hubs, said knives lying against one side wall of said projections of said respective hubs, annular outwardly opening grooves on said hubs being located on opposite sides of saidprojections for the re- I 'ception of said springs, a wall of each said groove defining an opposite side wall of each said projection, each said-opposite side wall sloping slightly toward the longitudinal axis of said shaftin a direction toward said 6 against said knives on said adjacent ones of said hubs by reason of said sloping opposite side walls to thereby maintain said knives flatly against said one side wall of each said projection. 

1. Apparatus for the longitudinal slitting of narrow strips of web material such as paper, foil and the like, comprising a rotatable shaft, a plurality of annular adjacent hubs mounted along said shaft for rotation therewith, circular knives and flat annular flexible springs seated on each of said hubs, radially extending shoulder projections on said hubs, said knives lying against one side wall of said projections of said respective hubs, annular outwardly opening grooves on said hubs being located on opposite sides of said projections for the reception of said springs, a wall of each said groove defining an opposite side wall of each said projection, each said opposite side wall sloping slightly toward the longitudinal axis of said shaft in a direction toward said knives on adjacent ones of said hubs, and the diameter of said grooves being slightly greater than the diameter of the inner annular edge of said springs, whereby said springs are made to flex radially when seated within their respective grooves to thereby positively secure said springs in place, and whereby said springs bear against said knives on said adjacent ones of said hubs by reason of said sloping opposite side walls to thereby maintain said knives flatly against said one side wall of each said projection. 